Solve for z_4
z_{4}=-1-3i
Assign z_4
z_{4}≔-1-3i
Share
Copied to clipboard
z_{4}=\frac{\left(2-4i\right)\left(1-i\right)}{\left(1+i\right)\left(1-i\right)}
Multiply both numerator and denominator of \frac{2-4i}{1+i} by the complex conjugate of the denominator, 1-i.
z_{4}=\frac{\left(2-4i\right)\left(1-i\right)}{1^{2}-i^{2}}
Multiplication can be transformed into difference of squares using the rule: \left(a-b\right)\left(a+b\right)=a^{2}-b^{2}.
z_{4}=\frac{\left(2-4i\right)\left(1-i\right)}{2}
By definition, i^{2} is -1. Calculate the denominator.
z_{4}=\frac{2\times 1+2\left(-i\right)-4i-4\left(-1\right)i^{2}}{2}
Multiply complex numbers 2-4i and 1-i like you multiply binomials.
z_{4}=\frac{2\times 1+2\left(-i\right)-4i-4\left(-1\right)\left(-1\right)}{2}
By definition, i^{2} is -1.
z_{4}=\frac{2-2i-4i-4}{2}
Do the multiplications in 2\times 1+2\left(-i\right)-4i-4\left(-1\right)\left(-1\right).
z_{4}=\frac{2-4+\left(-2-4\right)i}{2}
Combine the real and imaginary parts in 2-2i-4i-4.
z_{4}=\frac{-2-6i}{2}
Do the additions in 2-4+\left(-2-4\right)i.
z_{4}=-1-3i
Divide -2-6i by 2 to get -1-3i.
Examples
Quadratic equation
{ x } ^ { 2 } - 4 x - 5 = 0
Trigonometry
4 \sin \theta \cos \theta = 2 \sin \theta
Linear equation
y = 3x + 4
Arithmetic
699 * 533
Matrix
\left[ \begin{array} { l l } { 2 } & { 3 } \\ { 5 } & { 4 } \end{array} \right] \left[ \begin{array} { l l l } { 2 } & { 0 } & { 3 } \\ { -1 } & { 1 } & { 5 } \end{array} \right]
Simultaneous equation
\left. \begin{cases} { 8x+2y = 46 } \\ { 7x+3y = 47 } \end{cases} \right.
Differentiation
\frac { d } { d x } \frac { ( 3 x ^ { 2 } - 2 ) } { ( x - 5 ) }
Integration
\int _ { 0 } ^ { 1 } x e ^ { - x ^ { 2 } } d x
Limits
\lim _{x \rightarrow-3} \frac{x^{2}-9}{x^{2}+2 x-3}